The present invention relates to improvements in fiber classifying systems and more particularly to a mechanism for handling reclaimed waste fibers and separating the short unusable fibers from the usuable fibers.
In a wastepaper reclamation mechanism, wastepaper is processed usually in a refiner vat where the paper is first immersed in a liquid composition in which the inks and tars are soluble. The paper is then passed through a refiner to separate the fibers, and the fibers in suspension are then in condition for forming a paper web. However, the refined fibers can be substantially upgraded by moving undesirable fines which include fibers too short to have any substantial binding effect on the paper web. In the refining of the paper, short fibrils form on the stems of the longer fibers, and these fibrils fall off to form an abundance of fines. These fines not only do not contribute to the strength and quality of the paper, but detract from its formation in that they block the flow of water as the web is being formed in the dewatering operation.
It is accordingly an object of the invention to provide an improved classifier for use in a recycled fiber preparation which separates nonusuable fines from usable fibers in a continuing operation.
A further object of the invention is to provide a classifier of the type above described which is capable of continued operation in substantial volumes.
An important advantage of the invention is to provide an improved classifier for recycled fiber preparation wherein a proportionate amount of fines removed from the pulp is readily controllable.
A feature of the fiber classification mechanism is to have a controlled split of the flow passing through a screen critical size. For example, a flow is passed through a main chamber which is separated from a second chamber with 25% of the flow passing through a screen therebetween into the second chamber and 75% not going through the screen but continuing on through the first chamber flowing through an outlet. With fine holes in the screen as small as from 0.010 to 0.090, there will be a much higher probability of the fine particles from the stock going through the screen plate. Thus, the 25% effluent passed through the screen will have a much higher concentration of fine fibers than the 75% passing directly through the first chamber.
Other objects, advantages and features, as well as equivalent structures and methods which are intended to be covered herein, will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims, and drawings in which: